Ninth time's the charm, sometimes! At least that's Microsoft's hope with IE9, which they've just announced at Mix, brings new HTML5 support (including HTML5 video!), hardware-accelerated 2D graphics, and a totally new JavaScript engine—and no XP support.

Microsoft's just demoed the latest build of IE9, the final version of which doesn't yet have a release date, and for something as sleepy as a browser, it's pretty cool. Here's what's new:

HTML5

HTML5 is basically the talk of the town right now, assuming your town is populated exclusively by web developers and Apple apologists. It's magic! It's going to save the internet! It's going to kill Flash! Etc. But really, it's more subtle than that: It's the next version of the entire language that underlies the web—HTML—and it supports a lot of interesting features, which will make websites behave more like apps. Firefox, Safari, Chrome and Opera have pretty much left Microsoft in the dust in terms for HTML5 support. Until now! Here are the HTML5 features Microsoft says IE9 will support:

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• h.264 video: When people talk about HTML5 killing Flash, this is what they're talking about. Some video sites, like YouTube and Vimeo, have been experimenting with video playback that doesn't require a plugin to play. h.264 is the format standard the big sites have chosen to go with, and now Internet Explorer will support it.

• Embedded Audio: Just as the video tag allows for video to be embedded directly into a page without a plugin, the audio tag allows audio files to be embedded straight into the page. IE9 supports MP3/AAC codecs.

• Scalable Vector Graphics: Scalable vector graphics allow for the creation of certain types of graphics that scale perfectly—because they're drawn as vectors, not plain images. It can also allow for rudimentary, Flash-style animations.

• CSS3: CSS is essentially what the web is formatted with, and Internet Explorer's various CSS compatibilities have been maddening since, well, forever. IE9 supports more standards-based CSS3—including Selectors, Namespaces, Color, Values, Backgrounds and Borders and fonts—and should support more before launch. They're finally trying, is the point.

The New JavaScript Engine

Modern web apps are loaded with JavaScript, to the point that new browsers are practically measured by how fast they can render it. (A faster JavaScript engine means sites like Gmail, Facebook and even Gizmodo don't just load faster, but run more quickly.) Here's how Microsoft says IE9 measures up right now:

Keep in mind that this is a WebKit-designed test, and that IE9 isn't ready for release yet—Microsoft says they'll still improve the rendering speed. And really, while IE9 might not outpace the fastest browsers out there, it's at least close. And hilariously faster than IE8. In the onstage demo, IE9 didn't do terribly well on the Acid3 test, either, scoring a mediocre 55/100, which they vowed to improve. But again, they're at least trying, and when you've got the market share (and history of ignoring standards) that Microsoft does, this is, again, worth a lot.

2D Acceleration

Internet Explorer nine adds DirectX video acceleration for SVG graphics and even text rendering, which will make some SVG graphics and CSS3 rendering faster, but also applies to text rendering, which makes the entire browsing process a bit smoother.

HTML5 video rendering is much, much smoother than in Chrome (demonstrated onstage), simply because of Direct2D video rendering—Microsoft was able to demonstrate two 720p HD videos playing smoothly in the same browser window, while Chrome choked on just one. Getting this acceleration doesn't require any extra code on the website's part, though developers won't be able to depend on this kind of video acceleration in their webpages, since it's unique to IE9 and Windows, for now. More than allowing for absurd demos like this, what this means is that any video played back via the video tag in IE9 will simply use less CPU power than it would in another browser, which is an objective improvement. (Note: This won't be available on Windows XP.)

Additionally, some Javascript rendering can also be offloaded to the GPU, which, again, helps speed along rendering and responsiveness for complicated web apps.

A lot of what Microsoft is doing here could be accurately described as catchup. And aside from the 2D acceleration features, there's really not much new here, as far as your average browser is concerned. But Internet Explorer adoption is inevitable, and for Microsoft to embrace modern web standards—at least more than they have in the past—will have a measurable, positive effect on the internet, and the people who browse it. (From work, which I'm fairly sure is the only place where the computer-literate people use IE anyway.)

A Clean Break

It's hinted on Microsoft's IE9 site that some of the features of IE9 won't be compatible with XP, and some commenters have told me the prerelease version doesn't run on the aging OS. The truth, as confirmed by Mary Jo Foley, is more severe: IE9 will not support Windows XP.

A clean break at some point is inevitable, but this isn't going to go over too well with the millions of XP loyalists still out there.

The Preview

You can actually try it now, though some of the features—most conspiciously HTML5 video—aren't yet there, and the interface is still pretty barebones. (There's no proper address bar, for example, but just a "go to" popup window. This is a developers' test tool, really.) The download's available here.